1. Field of the Invention
The present invention relates to an method for cleaning and coating rod. More particularly, it relates to an method for descaling, cleaning and coating rod, prior to the drawing of the rod.
2. Description of the Prior Art
In the production of wire from a raw material such as steel rod (also commonly called "wire") the rod is passed through a plurality of drawing dies, each of which reduce the cross sectional area of the rod. As received from the mill, the raw rod has "scale" on its outer surface. This scale is comprised of impurities such as primary and secondary metal oxides and other brittle substances. Prior to passing the rod through the drawing process, this "scale" must be removed because if the raw rod is fed directly into the dies, the scale acts as an abrasive and clogs and destroys the dies. Thus, a need exists for processes which will remove the scale and prepare the rod for drawing.
Further, because the rod is drawn by pulling the wire through a restricted opening thereby developing high frictional heat, it is desirable to lubricate the surface of the rod in order to permit the smooth passage of the rod through the drawing dies. To accomplish this, it is desirable to coat the cleaned surface of the rod with a dry coating of borax or lime which acts as a carrier for the lubricant used in the drawing process.
A prior method for removing the scale on the outer surface of the rod, was to "pickle" the rod, that is soak the rod in an acid bath. This method presents extensive problems not only in the handling of the material, but also in the neutralizing and disposal of the spent acid. Moreover, in recent years, mainly because of ecological restrictions, acid pickling is being prohibited at more and more locations.
Other suggested methods employ a variety of mechanical descalers such as cascading steel balls and tapered abrasive bars which are used as cleaning or abrading devices for the rod. Examples of these devices are shown in U.S. Pat. Nos. 2,975,506 and 2,703,550. While the apparatus of these two prior patents is an improvement over the conventional pickling system, they both lack the effectiveness, compactness, continuity and reliability of the new improved apparatus and method of this invention. Thus, a need exists for a convenient, continuous process and apparatus for processing raw rod to produce an acceptable product for direct feeding to drawing benches.
An example of an apparatus for carrying out a continuous process for descaling, cleaning and coating of rod with a borax or lime solution prior to drawing, is shown in my basic U.S. Pat. No. 3,641,970, issued Feb. 15, 1972, entitled "Apparatus For Preparing Wire For Drawing," of which this application comprises an improvement.
It is therefore an object of this invention to provide a continuous process for cleaning and coating rod to produce cleaned rod having a coating of lime or other suitable substance baked thereon.
Another object of this invention is to provide a compact, self-contained apparatus which treats raw metal rod, descales it, cleans it, applies a coating of lime or borax solution thereto and electrically heats the rod to lessen the thermal shock to the rod as it is drawn through the die.